creatingObserver.js

import { Observable } from 'rxjs';

var randomNumberGenerator = Observable.create(function(observer) {
  setTimeout(function() {
    
    var randomNumber = Math.floor(Math.random() * 100);
    
    if(randomNumber == 13) {
      observer.error("Incorrect Random Number Generated");
    } else if(randomNumber == 99) {
      observer.complete();
    } else {
      observer.next(randomNumber);
    }
    
  }, 1000);
});

randomNumberGenerator.subscribe({
  next: function(data) {
    console.log("Input Data is: " + data)
  }, error: function(errorMessage) {
    console.log("Recieved the error with following message: " + errorMessage);
  }, complete: function() {
    console.log("Observable has completed Execution");
  }
})